In spite of studies on lots of substances aimed at the development of therapeutic agents for androgenetic alopecia, a substance which can be used as a safe and effective therapeutic agent for androgenetic alopecia has not been discovered yet. Minoxidil, which has been used as a therapeutic agent for hypertension, was found to bring about hypertrichosis as its side effect [British Journal of Dermatology, 101, 593–595 (1979)]. At present, it is used as a therapeutic agent for androgenetic alopecia, but is not completely satisfactory in respect of effectiveness, safety and side effect.
On the other hand, a large number of plant extracts have been conventionally used for the treatment of androgenetic alopecia. For example, an extract of Swertia japonica Makino, which is believed to have the activity to accelerate blood flow in capillary, is employed as a hair-growing agent [Tokushima Journal of Experimental Medicine, 9, 37–59 (1962)]. However, its effect is not sufficient.
An example of a known hair-growing agent comprising a lysophosphatidic acid or a phosphatidic acid is a minoxidil liposome preparation containing a lysophosphatidic acid or a phosphatidic acid as a liposome constitutive-vehicle (U.S. Pat. No. 5,030,442). Also known are a hair-nourishing agent comprising a phosphatidic acid having a fatty acid residue having a carbon chain with odd carbon number (Japanese Published Examined Patent Application No. 41363/88) and a cell activator comprising a phosphatidic acid having branched-chain fatty acid residues (Japanese Published Unexamined Patent Application No. 7205/86). However, there has not been known a hair-growing agent comprising a lysophosphatidic acid as an active ingredient or a hair-growing agent comprising a phosphatidic acid wherein all fatty acid residues are straight-chain fatty acid residues having an even number of carbon atoms. A mixture of some phospholipids including a phosphatidic acid is known to have apoptosis-inhibiting activity (WO 97/09989). Also known is a hair-growing agent comprising a phospholipid mixture (DE3222016 A1, DE4113346 A1).
WO 96/00561 describes a hair-growing agent comprising proanthocyanidin. Japanese Published Unexamined Patent Application No. 315947/97 describes a hair-growing agent comprising a protein kinase C (PKC)-specific inhibitor. It is known that tocopherol has hair-growing activity [“Ke no Igaku” (Medical Science of Hair), p. 283, Bunkodo (1987); Hair Science, p. 80, Japan Hair Science Association (1986)]. However, there is no report on a hair-growing agent comprising a phosphatidic acid and proanthocyanidin as active ingredients, a hair-growing agent comprising a phosphatidic acid and a protein kinase C-specific inhibitor as active ingredients, or a hair-growing agent comprising a phosphatidic acid and tocopherol as active ingredients.